The separation of many classes of compounds by selective adsorption on molecular sieves or zeolites as well as other adsorbents is well known. For example, as disclosed in U.S. Pat. No. 4,048,205, methyl esters of fatty acids of various degrees of unsaturation may be separated from mixtures of esters of saturated and unsaturated fatty acids with X or Y zeolites exchanged with a selected cation. Further, in U.S. Pat. No. 4,353,838 it is disclosed that monoethanoid fatty acids may be separated from diethanoid fatty acids with cross-linked polystyrenes, e.g. "Amberlite".
The process of separating triglycerides described herein has many potential uses, for example, the fractionation of triglycerides, e.g., palm olein. Also oils, such as soybean oil, can be processed to give fractions which are enriched or depleted in unsaturation.
Another important application of my separation process resides in its utility in triglyceride synthesis. Cocoa butter, for example, is a high value natural product consisting predominantly of a mixture of particular triglycerides where the 2-position of glycerol is esterified with an oleyl group and the 1- and 3-positions are esterified with either the palmitoyl or the stearyl group. Both the palmitoyl and stearyl groups are fully saturated, i.e., no double bond unsaturation exists on either groups' hydrocarbon chain. However, the oleyl group is unsaturated to provide the glycerides with a single site of unsaturation. The cocoa butter being primarily monounsaturated has been referred to as a monounsaturated triglyceride (MUT). Cocoa butter is a predominant component in chocolate confections. It is believed that large quantities of triglycerides could be synthesized and used as cocoa butter extenders by reaction of free fatty acids with glycerol or by selective hydrogenation of polyunsaturated triglycerides, followed by separation of the resulting mixtures by degree of unsaturation.
I have discovered combinations of zeolites, carbons and desorbents which separate the triglycerides based on differences in unsaturation. The triglycerides which are adsorbed preferentially to other triglycerides are concentrated in the extract. The other triglycerides, therefore, are removed from the mixture of triglycerides and are concentrated in the raffinate of the adsorptive separation apparatus.